Fmergency-stop means for elevator cars and counterweights



Oct. 24, 1933. ARNOLD 1,932,060

EMERGENCY STOP MEANS FOR ELEVATOR CARS AND COUNTERWEIGHTS Filed May 3 19 2 Sheets-Sheet 1 Lowest Lfhdz'ng INVENTOR Edwin E flrnold.

/ ATTORNEY Oct. 24, 1933.

E. E. ARNOLD EMERGENCY STOP MEANS FOR ELEVATOR CARS AND COUNTERWEIGHTS Fig. 3.

Filed May 31, 1930 2 Sheets-Sheet 2 Fig. 2.

AfTORNEY Patented Oct. 24, 1933 rMsR TEE

err-rear time GENCY-STOP MEANS FOR ELEVATOR CARS AND COUN'EEEWEIGHTS Edwin E. Arnold, Pittsburgh, Pa., assignor to Westinghouse Electric &'Manufacturing Company, a corporation of Pennsylvania Application May'31, 1930i Serial No. 458,055

9 Claims. o1. 187-6 '7 My invention relates to safety devices for increasing the safety of elevator installations and more specifically to means for aiding thebufiers in stopping elevator cars which have overrun V their'paths of normal travel.

In the elevator art, it has been a co Such a buffer commonly has a' piston'stroke of mmon practice to provide for emergency stopping of an elevator car, which has run past its limits of travel, by placing an oil buffer in a suitable position.

several feet, and, duringthe stroke of the piston, it must dissipate the kinetic energy of the moving car and its load, and bring it to rest.- Ithas'also been common to provide a buffer to check the speed of the, counterweight and bring it to a smooth stopat its limit of travel.

Such buffers, as designed and used, have gener-.

ally given satisfaction with the low-speed elevators of the past. But, with the present high-speed elevators and theincreasing demand for superhigh-speed elevator service, the use of the ordinary oil buffer becomes less and less satisfactory. Such buffers are diflicult to design for high-speed service, have a long stroke and are, consequently,

difiicult'to install. I 1

t is, accordingly, an object 0 its normal stroke.

It is a further object of my f myinvention to provide additionaldecelerating means for checking the speed of an overrunning high-speed elevator car to such an extent that an ordinary buffer will beenabled to bring it smoothly to rest within invention to provide additional decelerating means which will retard the car at such rate that, bythe time it engages j the bufier, its speed will have been reduced to such value that the buiferis capable of retarding the car and bringing it to rest in the usual manner.

t is also an object. of my invention to provide auxiliary decelerating means to check the speed of both the counterweight and the elevator car in order. that they may be bronght smoothly to rest without rebound.

Other objects of my invention will become evident from the following detailed description, takenin conjunction with the accompanying drawings, in which:

brake shoes of modified form in the lowe of the elevator hatchway, and

r portion Fig. 4 is a detail view showing a vertical section of a modified counterweight decelerator.

in accordance with my invention, I provide a combination of friction-brake and oil-buffer retardation for the elevator car, and a fluid displacement decelerator for the counterweight.

Referring more particularly to the drawings, the apparatus shown in Fig. 1 comprises a car C suspended by a cable Co. which passes over a hoist sheave S to a counterweight CW in the usual manner.

The car C runs up and down a hatchway H between guide rails, in the usual manner, but, for the sake of clearness, the guide rails are not shown. A pair of brake shoes 1 and 2 are mounted on diametrically opposite sides of the car and areseparated from the rigid structure of the car by rubber pads or'other elastic supports 3. The brake shoes 1 and 2 extend the entire length of the car height, but the rubber pads or elastic supports are provided only near the ends. The central portions of the brake shoes are flexible and exert only a nominal contact pressure onthe cooperating stationary brake shoes.

Pairs of stationary brake shoes 6' are rigidly mounted in the hatchway near theupper and the lower limits thereof. The stationary brake shoes are so spaced and positioned that they will have frictional engagement with the brake shoes carriedby the elevator car when the car travels of the hatchway. The lower pair of stationary brake shoes 6 is mounted below the terminal floor and just above the usual buffer 19 which is mounte ed on the bottom of the pit.

Each of the stationary brake shoes 6 is mounted upon'a backing taper plane '7 which is rigidly fixed in the hatchway. The structure of a brake shoe '5 and its backing taper plane is shown more detail in Fig. 2 where it willbe seen that the brake shoe 6 is slidably secured to the backing taper plane by bolts 8 and 9 which extend loosely through slots 10 in'the shoe. For locking the brake shoe in its projected or operative posia f becomes a piston in this chamber.

,.j the car will engage the buffer 19.

outer wall of the hatchway. The normal position of the brake shoe 6 is the projected or operative position, as shown in Fig. 2, but it is released by retracting the bolt 11 when it is necessary to release an elevator car which has moved into engaging relation therewith.

By the use of suitable brake-lining material 5, a very high co-eflicient of friction may be obtained between the engaging surfaces of the brake shoes 1 and 2, carried by the car, and the stationary brake shoes 6. However, the surfaces in contact between the brake shoes 6 and their backing taper planes '7 may be smooth and well lubricated, whereby the coefficient of friction is very low. Consequently, when the brake shoes 6 are released by withdrawing the bolts 11, they will very readily move with the car and, as they do so, they will move away from the car toward the inactive or disengaging position.

Mounted in the hatchway, are the usual limit switches 16 and 17 which function to cut off the power and deenergize the elevator motor when the car approaches either limit of the hatchway.

A decelerator 21 is provided for decelerating the counterwei ht in case the elevator car runs through its extreme limits of travel upward. The decelerator 21 comprises a fluid chamber of somewhat greater depth than the maximum overtravel of the counterweight in its extreme position when the car is at a position which is a safe distance from the extreme top of the hatchway. The opening in this chamber is of a size to more or less closely fit the cross sectional contour of the counterweight, and the counterweight of itself, By tapering the opening toward the bottom, the clearance between the counterweight and the walls of the chamber will become more restricted as the counterweight descends and the clearance may be so graduated that the escape of fluid through this clearance space will offer the proper resistance to effect slowdown at safe predetermined rates. The curve shown in conjunction with the counterweight decelerator shows how the velocity of the J counterweight may be reduced as it enters the chamber. The chamber may be of reinforced concrete or any other suitable material and is provided with a turbulence and displacement chamber 22 to receive the displaced fluid.

My invention may be more readily understood, I

-' will engage the limit switch 17 which will cause the power to be cut-off and the elevator motor to be deenergized in a well known manner. As the car continues down the shaft, its brake shoes 1 and 2 will be carried into engagement with the lower pair of stationary brake shoes 6 which will apply a gradually increasing decelerating force to the car as it runs into the shoes. When the lower ends of the car brake shoes pass below the lower ends of the stationary brake shoes 6, As the car brake shoes pass below, and out of engaging relation with, the stationary brake shoes, the decelerating force applied thereby decreases. But the decelerating force applied by the buffer is in- I creas ng while the decelerating force applied by finally bring the car to rest by a combination of friction and oil-buffer retardation.

The curve in Fig. 1 shows how the velocity of the car is reduced after the car engages the stationary shoes. The velocities of the elevator car are graphically represented an abscissa: at various positions of the platform of the car in the hatchway corresponding to points on the vertical axis of reference. The horizontal line V represents the velocity of the car at a time when the car platform has attained a corresponding vertical position and its brake shoes are entering into engagement with the stationary brake shoes. The horizontal line V1, represents the velocity of the car at the instant when the car engages the buffer. As shown by the two portions of the curve, the characteristics of the deceleration by friction may be different than that by buffer. By proper adjustment, however, the curves will join smoothly together, and, after the velocity of the .car has been reduced to a value V1 by the frictional retardation, it may be smoothly brought to rest by the ordinary buffer.

Assuming that the elevator car runs past its limits when travelling in the upward direction, it will engage a limit switch 16 which will cause the elevator motor to be deenergized in the usual manner. r

As the car continues upward, the counterweight CW will enter the chamber 21 where it will act as a piston on the fluid contained therein. The rate at which the fluid may escape is limited by the clearance space between the inner walls of the chamber and the counterweight. As previously set forth, the clearance may be graduated to cause a predetermined safe rate of deceleration of the counterweight. The'fluid is thrown up into a turbulence-and-displacement chamber 22 as the counterweight descends The car, in its travel upward, runs between the stationary brake shoes 6 which bring it to rest and prevent cable slack and consequent dangerous rebound.

In Fig. 3, I have shown a modification of my invention wherein brake shoes of a different type are mounted at the bottom of the hatchway.

The remainder of the system is in all respects similar to that shown in Fig. 1, hence the complete system is not shown in Fig. 3.

In this form of my invention, the lower brake shoes 36 are larger than the brake shoes 6 in Fig. 1 and are releasably supported by hooks 38 125 which are engaged by hooks 39 pivotally mounted on a pivot 40 on the wall of the hatchway. Each of the pivotally mounted hooks 39 is provided with an actuator 11 which protrudes into the hatchway tosuch position that the passage of an elevator car will cause it to rotate the hook 39 about its pivot point 40 to thereby unlatch the hook 38 and release the brake shoe 36. The actuator lever 41' may, however, be mounted at any other position, depending upon the position at which it is desired to apply the braking force. The hook 39 may also be rotated to its unlatching position by suitable electromagnetic means, the energization of which may be controlled by the limit switch 17 or by suitable contacts on the floor selector or elsewhere. The brake shoe 36 and the backing plane 37 are provided with cooperating inclined surfaces which cause the brake shoes to be projected into the hatchway to its operative position as it descends.

An adjustable screw stop 42 is provided under each brake shoe 36 to limit the descent thereof. It will be apparent that the greater the distance of descent permitted by the screw stop, the great-' ,V are provided in 45 er the braking force applied to the; brake shoes 1 a'nd2 carried by the car. I

previously set forth. "In this form of my invention,'an elevator car, descending below its nornial limits 'of travel, will first trip the limit switch 1'7 which will deenergize the elevator motor in the usual manner.

Asthecar'continues downward, it strikes the actuators 41, thereby releasing 'the brake shoes 36,'which begin to descend at the instant when they are released. But the shoes 36 must start from zero velocity whereas the car already has a high velocity at the instant the shoes are released. Consequently, by the time the shoes 36 are projected to the operative position, the car has run into a position between them, so that the full length of the car shoes is'adjacent the braking surface, and the braking force is applied suddenly. In other words, the car runs in between the shoes 36 without any braking force having been applied and then the braking force is applied suddenly. The initial braking force is higher in this form of my invention.

As the car passes below the brake shoes 36, the braking force applied thereby gradually diminishes." At the position where the car emerges from between the brake shoes, it engages the buifer 19 which applies a gradually increasing retarding force, whereby the car is brought to rest by a combination of friction and oil-buffer retardation. By proper adjustment of the brake N shoes 86 and the buffer 19, it is possible to apply a decelerating force which is practically constant. The curve represents the car velocities at various positions from the position where the maximum braking force is applied by the shoes 36 to the position where the car is brought to rest.

In Fig. 4, I have shown a modified form of my fluid counterweight decelerator. In this modification, cooperating reaction pockets 23 and 24 the sides of the counterweight CW and in the adjacent walls of the fluid chamber 21. The pockets may be of any form best adapted to trap the fluid and set up eddy currents and turbulence of the fluid as itescapes between the sides of the counterweight and the walls of the fluid chamber.

As the counterweight enters the fluid chamber and its velocity decreases, the decelerating force will tend to decrease, but, as an increasing number of pockets on the counterweight are carried into cooperative relation with the pockets in the walls of the fluid chamber, the decelerating force will tend to increase. Hence, by providing a proper number of pockets properly spaced on the counterweight, it is possible to obi: tain a uniform decelerating force or one that varies according to any desired function of the position and velocity of the descending counterweight.

In the form of the decelerator shown in Fig. 4,

1 a larger clearance may be allowed between the sides of the counterweight and the walls of the fluid chamber, and the clearance may be so graduated from top to bottom as to produce fluid velocities which will tend to set up a uniform decelerating force. In both modifications, the buoyiliary decelerating means which will become effective when an elevator car overtravels-in'the downward direction to reduce the speed thereof to' a degree commensurate with the capacityof the buifer which may then bring the car smoothly to restin the usual manner. Furthermore, ad ditional decelerating means have been provided which become eifectivewhena car overtravels in the upward direction to decelerate both the counterweight and the car, thereby preventing the rebound or falling back of the car which will occurif only'the counterweight is retarded. Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.-

I claim as my invention:

1. A braking device for decelerating an elevator car at its limits of travel comprising brake shoes resiliently mounted on diametrically opposite sides of an elevator car, stationary brake shoes mounted rigidly in the hatchway for engaging the brake shoes carried by the car and means for releasing said rigidly mounted brake shoes whereby they will move freely with the decelerated car toward the intermediate portion of the hatchway to disengage the car.

2. A braking device for decelerating an elevator car at its limits of travel comprising brake shoes carried by the elevator car, brake shoes mounted in the hatchway, and means for projecting said brake shoes to operative engaging position upon the approach of an elevator car.

3. A braking device, for decelerating an elevator car at its limits of travel comprising brake shoes carried by the elevator car, brake shoesmounted in the hatchway, and means for projecting said brake shoes to operative engaging position upon decelerated car to return toward an intermediate portion of the hatchway.

4. In a decelerator for an elevator counterweight, a fluid chamber having a vertical pas sageway to receive the counterweight as it approaches its limit of travel, said passageway having a tapered cross section slightly larger than the cross sectional contour of the counterweight to be received, whereby the clearance'between the counterweight and the wall of the chamber gradually decreases as the counterweight enters.

5. In a decelerator for absorbing the kinetic energy of a moving body, a fluid chamber comprising an elongated passageway for receiving said body, said passageway having a cross section larger than the cross section of the body to be received and so tapered that the clearance between the body and the walls of the chamber gradually diminishes as the body enters and the escape of "i the fluid is limited in accordance with the contour of the cross section of the chamber to' apply a constant force of deceleration to said body.

6. In a decelerator for an elevator counterweight, a fluid chamber having a vertical passageway for receiving said counterweighhsaid passageway having a cross section larger than the cross sectional contour of the counterweight by an amount which will permit the fluid to escape at such rate that a practically constant decelerating force will be applied, said passageway being of such length that the counterweight will be brought to rest from its maximum speed of entrance by the decelerating force applied.

'7. In a decelerator for an elevator counterweight, cooperating reaction pockets on the side walls of the fluid chamber, the number and spacing of said reaction pockets being such as to set up a substantially constant decelerating force as the velocity of the counterweight decreases.

9. In a decelerator for an elevator counter,- weight, a fluid chamber having a vertical passageway for receiving said counterweight, and fluidreceiving pockets on the sides of the counterweight and on the side walls of the counterweightreceiving passageway.

' EDWIN E. ARNOLD. 

